From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- fs/9p/vfs_addr.c | 351 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 351 insertions(+) create mode 100644 fs/9p/vfs_addr.c (limited to 'fs/9p/vfs_addr.c') diff --git a/fs/9p/vfs_addr.c b/fs/9p/vfs_addr.c new file mode 100644 index 000000000..e9e04376c --- /dev/null +++ b/fs/9p/vfs_addr.c @@ -0,0 +1,351 @@ +/* + * linux/fs/9p/vfs_addr.c + * + * This file contians vfs address (mmap) ops for 9P2000. + * + * Copyright (C) 2005 by Eric Van Hensbergen + * Copyright (C) 2002 by Ron Minnich + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 + * as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to: + * Free Software Foundation + * 51 Franklin Street, Fifth Floor + * Boston, MA 02111-1301 USA + * + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "v9fs.h" +#include "v9fs_vfs.h" +#include "cache.h" +#include "fid.h" + +/** + * v9fs_fid_readpage - read an entire page in from 9P + * + * @fid: fid being read + * @page: structure to page + * + */ +static int v9fs_fid_readpage(struct p9_fid *fid, struct page *page) +{ + struct inode *inode = page->mapping->host; + struct bio_vec bvec = {.bv_page = page, .bv_len = PAGE_SIZE}; + struct iov_iter to; + int retval, err; + + p9_debug(P9_DEBUG_VFS, "\n"); + + BUG_ON(!PageLocked(page)); + + retval = v9fs_readpage_from_fscache(inode, page); + if (retval == 0) + return retval; + + iov_iter_bvec(&to, ITER_BVEC | READ, &bvec, 1, PAGE_SIZE); + + retval = p9_client_read(fid, page_offset(page), &to, &err); + if (err) { + v9fs_uncache_page(inode, page); + retval = err; + goto done; + } + + zero_user(page, retval, PAGE_SIZE - retval); + flush_dcache_page(page); + SetPageUptodate(page); + + v9fs_readpage_to_fscache(inode, page); + retval = 0; + +done: + unlock_page(page); + return retval; +} + +/** + * v9fs_vfs_readpage - read an entire page in from 9P + * + * @filp: file being read + * @page: structure to page + * + */ + +static int v9fs_vfs_readpage(struct file *filp, struct page *page) +{ + return v9fs_fid_readpage(filp->private_data, page); +} + +/** + * v9fs_vfs_readpages - read a set of pages from 9P + * + * @filp: file being read + * @mapping: the address space + * @pages: list of pages to read + * @nr_pages: count of pages to read + * + */ + +static int v9fs_vfs_readpages(struct file *filp, struct address_space *mapping, + struct list_head *pages, unsigned nr_pages) +{ + int ret = 0; + struct inode *inode; + + inode = mapping->host; + p9_debug(P9_DEBUG_VFS, "inode: %p file: %p\n", inode, filp); + + ret = v9fs_readpages_from_fscache(inode, mapping, pages, &nr_pages); + if (ret == 0) + return ret; + + ret = read_cache_pages(mapping, pages, (void *)v9fs_vfs_readpage, filp); + p9_debug(P9_DEBUG_VFS, " = %d\n", ret); + return ret; +} + +/** + * v9fs_release_page - release the private state associated with a page + * + * Returns 1 if the page can be released, false otherwise. + */ + +static int v9fs_release_page(struct page *page, gfp_t gfp) +{ + if (PagePrivate(page)) + return 0; + return v9fs_fscache_release_page(page, gfp); +} + +/** + * v9fs_invalidate_page - Invalidate a page completely or partially + * + * @page: structure to page + * @offset: offset in the page + */ + +static void v9fs_invalidate_page(struct page *page, unsigned int offset, + unsigned int length) +{ + /* + * If called with zero offset, we should release + * the private state assocated with the page + */ + if (offset == 0 && length == PAGE_CACHE_SIZE) + v9fs_fscache_invalidate_page(page); +} + +static int v9fs_vfs_writepage_locked(struct page *page) +{ + struct inode *inode = page->mapping->host; + struct v9fs_inode *v9inode = V9FS_I(inode); + loff_t size = i_size_read(inode); + struct iov_iter from; + struct bio_vec bvec; + int err, len; + + if (page->index == size >> PAGE_CACHE_SHIFT) + len = size & ~PAGE_CACHE_MASK; + else + len = PAGE_CACHE_SIZE; + + bvec.bv_page = page; + bvec.bv_offset = 0; + bvec.bv_len = len; + iov_iter_bvec(&from, ITER_BVEC | WRITE, &bvec, 1, len); + + /* We should have writeback_fid always set */ + BUG_ON(!v9inode->writeback_fid); + + set_page_writeback(page); + + p9_client_write(v9inode->writeback_fid, page_offset(page), &from, &err); + + end_page_writeback(page); + return err; +} + +static int v9fs_vfs_writepage(struct page *page, struct writeback_control *wbc) +{ + int retval; + + p9_debug(P9_DEBUG_VFS, "page %p\n", page); + + retval = v9fs_vfs_writepage_locked(page); + if (retval < 0) { + if (retval == -EAGAIN) { + redirty_page_for_writepage(wbc, page); + retval = 0; + } else { + SetPageError(page); + mapping_set_error(page->mapping, retval); + } + } else + retval = 0; + + unlock_page(page); + return retval; +} + +/** + * v9fs_launder_page - Writeback a dirty page + * Returns 0 on success. + */ + +static int v9fs_launder_page(struct page *page) +{ + int retval; + struct inode *inode = page->mapping->host; + + v9fs_fscache_wait_on_page_write(inode, page); + if (clear_page_dirty_for_io(page)) { + retval = v9fs_vfs_writepage_locked(page); + if (retval) + return retval; + } + return 0; +} + +/** + * v9fs_direct_IO - 9P address space operation for direct I/O + * @iocb: target I/O control block + * @pos: offset in file to begin the operation + * + * The presence of v9fs_direct_IO() in the address space ops vector + * allowes open() O_DIRECT flags which would have failed otherwise. + * + * In the non-cached mode, we shunt off direct read and write requests before + * the VFS gets them, so this method should never be called. + * + * Direct IO is not 'yet' supported in the cached mode. Hence when + * this routine is called through generic_file_aio_read(), the read/write fails + * with an error. + * + */ +static ssize_t +v9fs_direct_IO(struct kiocb *iocb, struct iov_iter *iter, loff_t pos) +{ + struct file *file = iocb->ki_filp; + ssize_t n; + int err = 0; + if (iov_iter_rw(iter) == WRITE) { + n = p9_client_write(file->private_data, pos, iter, &err); + if (n) { + struct inode *inode = file_inode(file); + loff_t i_size = i_size_read(inode); + if (pos + n > i_size) + inode_add_bytes(inode, pos + n - i_size); + } + } else { + n = p9_client_read(file->private_data, pos, iter, &err); + } + return n ? n : err; +} + +static int v9fs_write_begin(struct file *filp, struct address_space *mapping, + loff_t pos, unsigned len, unsigned flags, + struct page **pagep, void **fsdata) +{ + int retval = 0; + struct page *page; + struct v9fs_inode *v9inode; + pgoff_t index = pos >> PAGE_CACHE_SHIFT; + struct inode *inode = mapping->host; + + + p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); + + v9inode = V9FS_I(inode); +start: + page = grab_cache_page_write_begin(mapping, index, flags); + if (!page) { + retval = -ENOMEM; + goto out; + } + BUG_ON(!v9inode->writeback_fid); + if (PageUptodate(page)) + goto out; + + if (len == PAGE_CACHE_SIZE) + goto out; + + retval = v9fs_fid_readpage(v9inode->writeback_fid, page); + page_cache_release(page); + if (!retval) + goto start; +out: + *pagep = page; + return retval; +} + +static int v9fs_write_end(struct file *filp, struct address_space *mapping, + loff_t pos, unsigned len, unsigned copied, + struct page *page, void *fsdata) +{ + loff_t last_pos = pos + copied; + struct inode *inode = page->mapping->host; + + p9_debug(P9_DEBUG_VFS, "filp %p, mapping %p\n", filp, mapping); + + if (unlikely(copied < len)) { + /* + * zero out the rest of the area + */ + unsigned from = pos & (PAGE_CACHE_SIZE - 1); + + zero_user(page, from + copied, len - copied); + flush_dcache_page(page); + } + + if (!PageUptodate(page)) + SetPageUptodate(page); + /* + * No need to use i_size_read() here, the i_size + * cannot change under us because we hold the i_mutex. + */ + if (last_pos > inode->i_size) { + inode_add_bytes(inode, last_pos - inode->i_size); + i_size_write(inode, last_pos); + } + set_page_dirty(page); + unlock_page(page); + page_cache_release(page); + + return copied; +} + + +const struct address_space_operations v9fs_addr_operations = { + .readpage = v9fs_vfs_readpage, + .readpages = v9fs_vfs_readpages, + .set_page_dirty = __set_page_dirty_nobuffers, + .writepage = v9fs_vfs_writepage, + .write_begin = v9fs_write_begin, + .write_end = v9fs_write_end, + .releasepage = v9fs_release_page, + .invalidatepage = v9fs_invalidate_page, + .launder_page = v9fs_launder_page, + .direct_IO = v9fs_direct_IO, +}; -- cgit v1.2.3-54-g00ecf